A political thinker should be read for insight, rather than doctrine. Karl Marx had two valid insights. He was mistaken about everything else. First, the natural result of un or lightly regulated capitalism is to accumulate wealth and income at the top. Second, partly as a result of this, capitalist economies experience increasingly destructive economic downturns.
Marx was mistaken about everything else. His most glaring mistake was to assume that among working class people loyalties of class are stronger than loyalties of race, nation, and ethnicity. The writings of Marx explain the Stock Market Crash of 1929, and the resulting Great Depression. They do not explain the First World War, the development of Italian Fascism and German Nazism, and the fact that America's white working class is a Republican constituency.
Marx was also mistaken in seeing an inevitable progression from primitive communism, to slavery, to feudalism, to capitalism. The revival of slavery in the Americas should have instructed him that this is not true.
Dialectical materialism is mythology. It is a kind of secular deity.
I see no value in the writing of Vladimir Lenin at all. Karl Marx did not advocate the totalitarian methods used in his name during the twentieth century. He did inspire them, so he is not completely innocent.